I'm trying to figure out: the property taxes I paid; do they fall under the category of cost basis or an expense?

I'm finishing up the duplex which I approximate should take about 1-2 more weeks.

We are in the research phase right to figure out the best way to structure the entity/partnership. 

I'm trying to figure out what is the proper way to get an estimated ARV after renovation of an apartment building. 

and I wonder how much they would pay per night or short term how do you figure that out..Most of the Air bnb s I have seen around here are modest homes  or like ADU';s  there are nice ones at the coast..

I'll need to figure out how to refine it. 

And some will take this further by saying that if there are landlord paid utilities, one can expect expenses to be an even higher percentage of rent (60% is a figure that gets tossed into play).Search the BP site to find threads that discuss those in greater detail.

I have approximately $40k cash to invest.

After reading the title I figured the tenant had held over for months ornmaybe a year.  

I'd focus on figuring out what companies you like in those markets then when you pick a market make sure you buy right in said market.